Custom MAC Prefixes in Eucalyptus 3.3.x to 3.4.x using SYSTEM Mode

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Eucalyptus Versions:  3.3.x to 3.4.x

Custom MAC Prefixes in Eucalyptus 3.3.x to 3.4.x using SYSTEM Mode

There are situations where cloud administrators would like to use Eucalyptus in SYSTEM mode on their network, but there are restrictions as to the MAC (media access control) [1] addresses that can be used on the network for security reasons.  To handle scenarios like this, cloud administrators have the ability to configure Eucalyptus to use a particular prefix (first two octets) [2] for the MAC addresses that will be handed out to instances, that the network administrator has set up [3].

To customize this prefix, the cloud administrator just needs to add the following entry into the /etc/eucalyptus.conf file on the Cluster Controller (CC):

VNET_MACPREFIX="<custom MAC address prefix >"

If the prefix "D0:D0" is to be desired, then the entry would resemble the following:

VNET_MACPREFIX="D0:D0"

After changing that value, make sure and start/restart the Cluster Controller (CC) using the following command where the Cluster Controller (CC) resides:

service eucalyptus-cc start|restart

After making that change, and an instance is launched, the cloud administrator should see the following:

  • Make sure the Cluster Controller (CC) is set to DEBUG logging (i.e. LOGLEVEL="DEBUG") in the /etc/eucalyptus/eucalytpus.conf file. The instance will show up getting the updated MAC prefix in the /var/log/eucalyptus/cc.log file on the Cluster Controller (CC):
2014-04-21 13:27:41 DEBUG 000014097 instIpSync | instanceId=i-811C3D96 CCpublicIp=0.0.0.0 CCprivateIp=0.0.0.0 CCprivateMac=D0:D0:81:1C:3D:96 CCvlan=-1 CCnetworkIndex=-1 NCpublicIp=0.0.0.0 NCprivateIp=0.0.0.0 NCprivateMac=D0:D0:81:1C:3D:96 NCvlan=-1 NCnetworkIndex=-1
  • On the Node Controller (NC) where the instance is running, there will be log entries in /var/log/messages, showing the instance's MAC address getting an IP from the DHCP server
Apr 21 13:28:46 odc-f-37 kernel: IN=br0 OUT=br0 PHYSIN=em1 PHYSOUT=vnet0 SRC=10.104.1.101 DST=10.104.254.0 LEN=334 TOS=0x10 PREC=0x00 TTL=128 ID=0 PROTO=UDP SPT=67 DPT=68 LEN=314
Apr 21 13:28:46 odc-f-37 kernel: IN=br0 OUT=br0 PHYSIN=vnet0 PHYSOUT=em1 SRC=0.0.0.0 DST=255.255.255.255 LEN=328 TOS=0x10 PREC=0x00 TTL=128 ID=0 PROTO=UDP SPT=68 DPT=67 LEN=308
Apr 21 13:28:47 odc-f-37 kernel: IN=br0 OUT=br0 PHYSIN=em1 PHYSOUT=vnet0 SRC=10.104.1.101 DST=10.104.254.0 LEN=334 TOS=0x10 PREC=0x00 TTL=128 ID=0 PROTO=UDP SPT=67 DPT=68 LEN=314

Using custom MAC prefixes in SYSTEM mode differs than STATIC mode because the cloud administrator isn't restricted by the granular definition of each MAC address:IP relationship that needs to be added to the /etc/eucalyptus.conf file.  

References

[1] MAC Address
[2] Organizationally Unique Identifier 
[3]Eucalyptus Jira Ticket DOC-542

 

 

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